where \(h\)  is the 125 GeV Higgs, \(A_\mu \)  and \(Z_\mu \)  the photon and \(Z\)  boson fields, \(T^3_\psi \)  is the eigenvalue of the third generator of \({\rm SU}(2)_L\)  when it acts on the left-handed component of \(\psi \) , so that \(T^3_\psi =\pm \frac{1}{2}\)  when \(\psi _L\)  arises from a doublet in the fundamental of \({\rm SU}(2)_L\) . Its one-loop contributions to the amplitudes \(h\rightarrow \gamma \gamma \)  and \(h\rightarrow \gamma Z\)  are [1]}
\({\cal A}^\psi _{\gamma \gamma }\approx \frac{4}{3} Q_\psi ^2 \ , \quad {\cal A}^\psi _{Z\gamma }\approx -\frac{1}{3} Q_\psi \frac{T^3_\psi -2Q_\psi s_W^2}{c_W} \ ,\) 
